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Home , Blackchin guitarfish, Giant guitarfish, Glaucostegus, Guitarfish, Rhina ancylostoma, Rhynchobatus

Supplementary Information for (Rhinidae) and giant (Glaucostegidae)

Generation lengths

There is a general lack of age and growth data for wedgefishes (Rhinidae) and giant guitarfishes (Glaucostegidae). Maximum age given by White et al. (2014) for female spp. (mixed samples of R. australiae and R. palpebratus) was 12 years. However, this figure alone is not useful to estimate generation length as White et al. (2014) did not provide female age at maturity, and the maximum age estimate was for a 183 cm total length (TL) individual, whereas R. palpebratus grows to 262 cm TL and R. australiae to ~300 cm TL (Last et al. 2016).

To provide a more realistic generation length estimate for large rhinid as well as large glaucostegid species (those species reaching ≥200 cm TL), data can be used from White et al. (2014) for the Giant ( typus):

• Female age at maturity: 7 years (taken from the growth curve) • Female maximum age: 19 years (for a 250 cm TL individual which is under but close to the maximum size of 270 cm TL; Last et al. 2016) • Calculated generation length: 13 years • Estimated generation length: 15 years (to account for the larger maximum size of the species compared with the largest individual aged)

For Glaucostegus cemiculus, Enajjar et al. (2012) found a female age at maturity of 5.1 years, and a maximum age of 14 years, which gives a generation length of 9.5 years. The largest specimen examined in this study was 198 cm TL, while the species reaches a maximum size of 265 cm TL; 9.5 years would therefore be an underestimate of generation length.

To ensure consistency across assessments, 15 years was applied as an estimated generation length to large (≥200 cm TL) rhinid and glaucostegid species, and 10 years was applied to smaller species (<200 cm TL) (Table 1).

Table 1. Estimated generation lengths for wedgefishes (Rhinidae) and giant guitarfishes (Glaucostegidae).

Maximum Size Estimated Estimated 3 Family Species (cm total length) Generation Generation Length (years) Lengths (years) Rhinidae 270 15 45 Rhinidae 300 15 45 Rhinidae Rhynchobatus cooki 81 10 30 Rhinidae Rhynchobatus djiddensis 310 15 45 Rhinidae Rhynchobatus immaculatus 99* 10 30 Rhinidae Rhynchobatus laevis 200 15 45 Rhinidae Rhynchobatus luebberti 300 15 45 Rhinidae 262 15 45 Rhinidae Rhynchobatus springeri 213 15 45 Rhinidae Rhynchorhina mauritaniensis 275 15 45 Glaucostegidae Glaucostegus cemiculus 265 15 45 Glaucostegidae Glaucostegus granulatus 229 15 45 Glaucostegidae Glaucostegus halavi 187 10 30 Glaucostegidae Glaucostegus obtusus 93 10 30 Glaucostegidae Glaucostegus thouin 300 15 45 Glaucostegidae Glaucostegus typus 270 15 45 *Immature male; maximum size suspected to be ~150 cm total length. Population reduction calculations

Table 2. Proportional decline over 3 generation lengths (30–45 years) for wedgefishes and giant guitarfishes for Iran. Landings data are for the category ‘’ which likely includes all rhinids and glaucostegids occurring locally, including Bowmouth Guitarfish (Rhina ancylostoma), Bottlenose (Rhynchobatus australiae), Whitespotted Wedgefish (R. djiddensis), Smoothnose Wedgefish (R. laevis), (Glaucostegus granulatus), and (G. halavi). Data source: FAO (2018).

Year Landings (t) Year Landings (t) 1997 880 1997 880 2016 295 2016 295 Proportional decline over 20 years 0.665 0.665 Annual proportional change 0.947 0.947 Generation length (years) 10 15 3 generation lengths (3 GL; years) 30 45 Proportion remaining 0.194 0.086 Proportional decline over 3 GL 0.806 0.914

Table 3. Proportional decline over 3 generation lengths (30–45 years) for wedgefishes and giant guitarfishes for Sindh, . Landings data are for the category ‘rhinobatid’ which likely includes all rhinids, glaucostegids, and rhinobatids occurring locally, including Bowmouth Guitarfish (Rhina ancylostoma), Bottlenose Wedgefish (Rhynchobatus australiae), Smoothnose Wedgefish (R. laevis), Sharpnose Guitarfish (Glaucostegus granulatus), Halavi Guitarfish (G. halavi), and Widenose Guitarfish (G. obtusus). Data source: Mauvis Gore, unpublished data.

Year Landings (t) Year Landings (t) 1999 902 1999 902 2011 252 2011 252 Proportional decline over 13 years 0.720 0.720 Annual proportional change 0.907 0.907 Generation length (years) 10 15 3 generation lengths (3 GL; years) 30 45 Proportion remaining 0.053 0.012 Proportional decline over 3 GL 0.947 0.988

Table 4. Proportional decline over 3 generation lengths (30–45 years) for wedgefishes and giant guitarfishes for Balochistan, Pakistan. Landings data are for the category ‘rhinobatid’ which likely includes all rhinids, glaucostegids, and rhinobatids occurring locally, including Bowmouth Guitarfish (Rhina ancylostoma), Bottlenose Wedgefish (Rhynchobatus australiae), Smoothnose Wedgefish (R. laevis), Sharpnose Guitarfish (Glaucostegus granulatus), Halavi Guitarfish (G. halavi), and Widenose Guitarfish (G. obtusus). Data source: Mauvis Gore, unpublished data.

Year Landings (t) Year Landings (t) 1994 921 1994 921 2011 178 2011 178 Proportional decline over 18 years 0.806 0.806 Annual proportional change 0.913 0.913 Generation length (years) 10 15 3 generation lengths (3 GL; years) 30 45 Proportion remaining 0.065 0.016 Proportional decline over 3 GL 0.935 0.984

Table 5. Proportional decline over 3 generation lengths (30–45 years) for wedgefishes and giant guitarfishes for Maharashtra, . Catch rate data are for myliobatoid rays (stingrays, eagle rays, butterfly rays, and devil rays) and while it does not include wedgefishes or giant guitarfishes, this can be used to infer declines given overlapping distributions, , and susceptibility to capture in the same fishing gear. Data source: Raje and Zacharia (2009).

Catch rate Year Catch rate Year (kg/hr) (kg/hr) 1990 0.65 1990 0.65 2004 0.24 2004 0.24 Proportional decline over 15 years 0.631 0.631 Annual proportional change 0.936 0.936 Generation length (years) 10 15 3 generation lengths (3 GL; years) 30 45 Proportion remaining 0.136 0.050 Proportional decline over 3 GL 0.864 0.950

Table 6. Decline in landings of ‘guitarfishes’ from in Chennai, Tamil Nadu, India. For rhinids, this grouping was reported to include Bowmouth Guitarfish (Rhina ancylostoma) and 'Rhynchobatus djiddensis'. The latter does not occur in the area, and hence the grouping would therefore include local ‘whitespotted wedgefish’ species i.e. Bottlenose Wedgefish (Rhynchobatus australiae) and Smoothnose Wedgefish (R. laevis). For glaucostegids, this grouping was reported to include Sharpnose Guitarfish (Glaucostegus granulatus) and Widenose Guitarfish (G. obtusus) but was also likely to include Giant Guitarfish (G. typus) and (G. thouin) which occur locally. Separate data were also provided for 'Rhynchobatus djiddensis', which would represent Bottlenose Wedgefish and Smoothnose Wedgefish. Data source: Mohanraj et al. (2009).

‘Guitarfishes’ ‘Rhynchobatus djiddensis’ Year Landings (t) Year Landings (t) 2002 278.7 2002 114.9 2006 38.3 2006 14.9 Proportional decline over 3 GL Dataset too short to reliably derive equivalent population reduction over three generations

Table 7. Proportional decline over 3 generation lengths (30–45 years) for wedgefishes and giant guitarfishes for . Landings data are for the category 'whitespotted wedgefishes' which likely includes all rhinids occurring locally including Bowmouth Guitarfish (Rhina ancylostoma), Bottlenose Wedgefish (Rhynchobatus australiae), Clown Wedgefish (R. cooki), Eyebrow Wedgefish (R. palpebratus), and Broadnose Wedgefish (R. springeri), and may also include glaucostegids (in any case, the trends can be considered representative of glaucostegids as well as rhinids). Data sources: DGCF (2015, 2017).

Year Landings (t) Year Landings (t) 2005 28,492 2005 28,492 2015 3,540 2015 3,540 Proportional decline over 11 years 0.876 0.876 Annual proportional change 0.827 0.827 Generation length (years) 10 15 3 generation lengths (3 GL; years) 30 45 Proportion remaining 0.003 0.0002 Proportional decline over 3 GL 0.997 0.9998

References

Directorate General of Capture Fisheries (DGCF). (2015). Capture Fisheries Statistics of Indonesia. Directorate General of Capture Fisheries, Jakarta, Indonesia.

Directorate General of Capture Fisheries (DGCF). (2017). Capture fisheries statistics of Indonesia by province. Ministry of Marine Affairs and Fisheries, Jakarta, Indonesia. Vol. 17 No.1. ISSN: 1858-0505. 326 pp.

Enajjar, S., Bradai, M.N. and Bouain, A. (2012). Age, growth and sexual maturity of the cemiculus in the Gulf of Gabès (southern Tunisia, central Mediterranean). Cahiers de Biologie Marine 53: 17–23.

Food and Agriculture Organization of the United Nations (FAO) (2018). FAO Fishstat Capture Production Database 1950-2015. Fisheries Information, Data and Statistics Unit. FAO, Rome, Italy. Available at: http://www.fao.org/fishery/statistics/software/fishstatj/en

Last, P., White, W., de Carvalho, M., Séret, B., Stehmann, M. and Naylor, G. (2016). Rays of the World. CSIRO Publishing, Clayton.

Mohanraj, G., Rajapackiam, S., Mohan, S., Batcha, H. and Gomathy, S. (2009). Status of elasmobranchs fishery in Chennai, India. Asian Fisheries Science 22: 607–615.

Raje, S.G. and Zacharia, P.U. (2009). Investigations on fishery and biology of nine species of rays in Mumbai waters. Indian Journal of Fisheries 56: 95–101.

White, J., Simpfendorfer, C.A., Tobin, A.J. and Heupel, M.R. (2014). Age and growth parameters of -like batoids. Journal of Biology 84: 1340–1353.